There has been a tendency in the past to look on wheelchairs as merely a means for providing limited transportation for invalids within a relatively small area. However with increasing opportunities for mobility by wheelchair users, and an increasing interest in sports activities in which the wheelchair user may participate, there has arisen a need for wheelchairs that--while comfortable and easy to use--are capable of being folded compactly for transportation in a car or plane, are lightweight, can accommodate the particular physical characteristics of the user, and are readily maneuverable for use in wheelchair sports. The wheelchair according to the present invention is one that fulfills such a need.
The wheelchair according to the present invention is constructed in a modular format. A base frame mounts the wheels, preferably comprising two rear drive wheels and two front caster-type wheels. The frame receives a pallet, and the pallet in turn supports a collapsible chair frame. The position of the pallet with respect to the frame can be easily adjusted to adjust the center of gravity of the wheelchair without repositioning the rear wheels vis-a-vis the frame. The chair frame can collapse into a substantially flat configuration on the pallet for ease of transportation. All wheels are connected to the frame utilizing a split-block construction that allows for ready removal of the wheels while insuring that they are maintained properly in place during use.
In order to maximize the maneuverability and versatility of the wheelchair according to the invention, toe and camber adjustments for the drive wheels are provided. The split-blocks that receive the spindles, or other shaft means, of the drive wheels are mounted for pivotal movement about an axis perpendicular to the axis of rotation of the rear wheels, to adjust the camber of the rear wheels. The blocks are mounted on the free ends of a leaf spring which is stationarily mounted to the frame at a central portion thereof. By flexing the ends of the leaf spring with respect to the frame, the toe of the drive wheels may also be readily adjusted.
Since ready removal of the drive wheels is desirable, the brake that is provided is mounted for pivotal movement about an axis generally parallel to the axis of rotation of the drive wheels so that the brake mechanism can be pivoted out of the way of the drive wheels to effect removal. An actuator for the brake may be moved through the brake-applying position to an over-center position to effect the locking of the drive wheels so that the user can dismount from the wheelchair without fear of it moving during dismounting.
The front wheels have vertically extending spindles, or other shaft means, which are received in a split-block assembly attached to the frame. A graspable component for effecting rotation of the front wheels about a vertical axis is attached to each spindle. The chair is mounted by the pallet in such a manner that one sitting in the chair may readily grasp the steering components for the front wheels and effect steering of the wheelchair.
It is the primary object of the present invention to provide a lightweight, comfortable and easy-to-use wheelchair that may be folded compactly for ready transportation, and which is readily utilizable in wheelchair sports, and on the wheelchair. This and other objects of the invention will become clear from an inspection of the detailed description of the invention, and from the appended claims.